Boston, Massachusetts (CNN) -- Auto manufacturer Toyota warned dealerships in 2002 that Camry owners were complaining about throttles surging and recommended adjustments in an electronic control unit to fix the problem, according to a document obtained by CNN.

The technical service bulletin went to every U.S. Toyota dealership in late August 2002 after some customers reported their vehicles were speeding up unexpectedly.

"Some 2002 model year Camry vehicles may exhibit a surging during light throttle input at speeds between 38-42 mph," the bulletin states. "The Engine Control Module (ECM) calibration has been revised to correct this condition."

Toyota, the world's largest automaker, has blamed acceleration surges on floor mats it says can trap accelerator pedals and recalled more than 2.3 million vehicles in January for sticky accelerator pedals. It has said that independent testing failed to find problems with its electronic throttle controls.

But Clarence Ditlow, the head of the nonprofit Center for Auto Safety, said the 2002 document doesn't talk about mechanical issues.

"If you look at this document, it says electronics," Ditlow said. "It says the fix is reprogrammed in the computer. It doesn't say anything about floor mats."

The internal Toyota document was given to CNN by a group of attorneys now seeking a nationwide class-action lawsuit against the company. Ditlow said the document -- not previously made public -- indicates Toyota knew much earlier about an electronic connection to sudden acceleration problems. He also said the bulletin was apparently ignored or hidden from the public not only by Toyota, but also by the National Highway Traffic Safety Administration.

"The government is really hiding this information from the consumer," Ditlow told CNN. "They're in a conspiracy with the auto industry to keep these out of the public's sight."

The attorneys now suing Toyota say the repair bulletin is proof the car company knowingly lied to the public about the causes of sudden acceleration, blaming floor mats or stuck gas pedals instead.

"They can fix these problems easily," said Tim Howard, a Northeastern University law professor who heads the legal group suing Toyota. "But it would cost them about $500 a car nationwide. If you have six [million] to seven million cars, you add the numbers -- it's between $4 [billion] and $5 billion. It's hard to actually tell the truth when those numbers are at the bottom of that truth."

NHTSA did not respond to requests for comment. And Toyota did not respond to questions about the bulletin, but it issued a statement to CNN attacking Howard and his fellow lawyers.

Howard and his legal team say they plan to appear in federal court in San Diego, California, later this week, trying to persuade a federal judge to combine the 88 individual lawsuits so far filed against Toyota into a single class-action litigation.